Semisynthesis of mallotus B from rottlerin: evaluation of cytotoxicity and apoptosis-inducing activity.

Shreyans K Jain, Anup S Pathania, Samdarshi Meena, Rajni Sharma, Ashok Sharma, Baljinder Singh, Bishan D Gupta, Shashi Bhushan, Sandip B Bharate, Ram A Vishwakarma

Index: J. Nat. Prod. 76(9) , 1724-30, (2013)

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Abstract

Mallotus B (2d) is a prenylated dimeric phloroglucinol compound isolated from Mallotus philippensis. There have been no reports on the synthesis or biological activity of this compound. In the present paper, a semisynthetic preparation of mallotus B is reported via base-mediated intramolecular rearrangement of rottlerin (1), which is one of the major constituents of M. philippensis. The homodimer "rottlerone" was also formed as one of the products of this base-mediated intramolecular reaction. Rottlerin (1), along with rottlerone (2c) and mallotus B (2d), was evaluated for cytotoxicity against a panel of cancer cell lines including HEPG2, Colo205, MIAPaCa-2, PC-3, and HL-60 cells. Mallotus B (2d) displayed cytotoxicity for MIAPaCa-2 and HL-60 cells with IC₅₀ values of 9 and 16 μM, respectively. Microscopic studies in HL-60 cells indicated that mallotus B (2d) induces cell cycle arrest at the G1 phase and causes defective cell division. It also induces apoptosis, as evidenced by distinct changes in cell morphology.